Figure 4. Oxidation of roGFP2-based probes expressed in E. coli co-cultivated with neutrophil-like cells.

E. coli cells expressing roGFP2-Orp1 from a plasmid were incubated in a 96-well plate reader. The ratio of the fluorescence intensity at excitation wavelengths of 405 and 488 nm was calculated and plotted over time. The arrow indicates the addition of medium, undifferentiated PLB-985 cells and differentiated, neutrophil-like PLB-985. Addition of neutrophil-like cells led to probe oxidation, as evidenced by the increase in the ratio of the fluorescence intensities (A). The probe oxidation in bacteria expressing the Grx1-roGFP2 fusion probe (B) and unfused roGFP2 (C) showed kinetics virtually identical to E. coli cells expressing roGFP2-Orp1.